Breech block and chamber for ordnance.



Patented July '29, I902.

C. HULMSTRUM. BREECH BLOCK AND CHAMBER FOR OBDNANCE.

(Application filed Jan. 3, 1902.

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BREEGH BLOCK AND CHAMBER FOR ORDNANGE.

. (App lication filed Jan. 3, 1902.)

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harass CARL HOLMSTRUM, OF GLASGOW, SCOTLAND.

SPECIFICATION forming part of Letters Patent No. 705,841, dated July 29, 1902.

Application filed January 3, 1902. Serial No. 88,367. (No model.)

To 00% whom zit may concern; v v

Be it known that I, CARL I-IQLMsTRGM, engineer, a subject of the King of Sweden and Norway, residing at Parkhead Forge Rolling Mills and Steel Works, Glasgow, Scotland, have invented certain new and useful Improvements Relating to Breech-Loading Ordnance, of which the following is a specification.

This invention relates to breech-loading ordnance and has special reference to the formation of the breech-block and its chamber.

The chief object sought in the construction 7 of the screw-threaded breech-blocks of ordnance is the shortest length compatible with security in closing the breech, so that the block shall be compara'tively light in Weight and capable of easy manipulation in a small space in opening and closing the breech. The length of the block must in all cases be such that the screw-threads will have sufficient surface area to resist the pressure in the gun. It is of great importance that-the threads should be so formed that a slight an gular displacement or incomplete closing of the bloclrwill not seriouslyimpair the extent of-the'area of the threads in contact with each other, so that the block will have a sat isfactory bearing-surface throughout its entire length. and will not lie loosely in the chamber, so as to odor through its threads insufficient resistance to the pressure arising on discharge of the gun to insure a safe locking. It is, furthermore, of importance that the block shall require only a comparatively small angular movement in being locked and unlocked.

Many attempts have been made to construct a breech-block which shall effectually fulfil the above requirements. Probably the best known form of block for such purpose is that in which the periphery is made in steps and with one or more gaps, the curved surface of each stop being threaded. There are, however, difficulties in connection with stepped blocks of this description. For instance, the

- threads cannot be made continuous from one step to another by reason of the abruptness of the radial'divisio'ns between the contiguous steps. Therefore in forming the said threads on the blocks the thread-cutting tool has to pass suddenlyfrom one surface to anposed to have the peripheryof the block of" volute or spiral'formation; but although in such case the screw-threads could be made continuous the locking of the block in the breech-chamber would be most unsatisfactory, owing to the great diminution of the resisting-surface ofthe threads if the block failed in the slightest degree to perform its full angular movement in the locking operation. Such a block would beimpracticable for use in ordnance because of its liability. to be blownout from the breech of the gun.

Now according to my invention I overcome all the above-stated objections by so constructing the block in cross-section that its contour or periphery presents a series of arcs of concentric circles described about the axis of the block, the successive arcs being joined by straight or curved surfaces, which, with the exception of the first and last, are so arranged as to avoid abrupt transition from one to another of the circular arcs. Thusnotwithstanding the fact that the periphery of the block has a series or two or more series of curved surface at different distances from the axis the threads can be made continuous throughout each entire series of such surfaces, except, of course, at the part where the gap or gaps are formed. The breech-chamber of the gun is similarly formed to receive the said block.

In order that my said invention may. be clearly understood and readily carried into effect, I will describe the same more fully, -with reference to the accompanying df'awings, "in which--=- Figures 1 and 2 are cross-scctionsof my improved block and breech-chamber, the former figure representing the block locked and-the latter unlocked. Fig. 3 is a development of the peripheral surface of this block. Figs. 4 and 5 are cross-sections of a modified form of my block and breech-chamber, the former figure representing the block locked and the latter unlocked. Fig. 6 is a development of breech end, of the gun.

On reference to the various figures it will be seen that the arcs a a (1 ,850., are not interrupted by radial surfaces, as hashitherto been the case with stepped blocks, my object being to avoida-ny abrupt or sudden separation ofone are from another except at the gap or gaps a, where there are no screw-threaded surfaces.

In Figs. 1, 2, and 3 the arcs a a a &c.,

' (all of which are described from the point my) are connected by straight surfaces afi that are tangential to the arcs of smaller radius and are joined to the arcs of larger radius by curves a.

In Figs. 4, 5, and 6 the concentric arcs a a a, &c., are connected by sloping or inclined surfaces a, which are curved where they meet said arcs.

In Figs. 7, 8, and 9 the said concentric arcs a a at? are connected by curves a of ogee formation, without any straight surfaces.

With the above-described forms of the block it. is practicable for the entire surface of the arcs a a a and their connecting portions to be made with uninterru pted threads. I am thus able to provide the series of arcs with continuous lockili'g for supporting the block in the breech-chamber against the endwise thrust or pressure, and consequently my improved block can be made appreciably shorter than the ordinary stepped blocks hitherto constructed.

It will be apparent that the periphery of my said block has no spiral or volute surfaces, but consists almost entirely of a series of concentric surfaces, so that a slight angular displacement of the block would not have the ticular degree of inclination or curvature of the surfaces joining the concentric arcs of my block so long as their abruptness is not such as to render the continuation of the threads upon them impracticable. Likewise I do not wish the formation of my block to be confined to any specific number of threaded segments and gaps, as of course their number will somewhat depend upon the dimensions of the block. In Figs. 1 to 6 I have shown one gap and five threaded segments and in Figs. 7 to 9 two gaps and six threaded segments. ments are located symmetrically around the block. I also wish it to be understood that my block can be mounted in any appropriate kind of swinging carrier and can be actuated by any suitable kind of breech mechanism. What I claim, and desire to secure by Letters Patentof the United States, is-

l. A breech-block which in cross-section comprises a series of concentric steps of different radii joined by surfaces other than radial with respect to the axis of the block so that the locking-surfaces can all be formed with continuous or uninterrupted screwthreads for the purpose specified.

2. A breech-block which in cross-section comprises a series of concentric steps of different radii joined by inclined surfaces substantially as and for-the purpose specified.

3. A breech-block which in cross-section In the'la'tter case the threaded seg- 1 r comprises a series of concentric steps of different radii joined by inclined surfaces that are approximately tangential to the concentric surfaces of larger radius and curved where they meet the concentric surfaces of the smaller radius substantially as and for purpose specified.

4. A breech-block which in cross-section comprises a series of concentric steps of different radii joined by curved surfaces of ogee formation substantially as and for the pur- 

